You've got lots of good advice here.. You mention that a sized case will not chamber - to be specific you cant close the bolt on a sized case. So there are only a few possibilities:
1) Case not trimmed adequately - seems you've addressed this already.
2) Cases are binding on the shoulder. Suggestions given vis FL die adjustment...
3) Cases binding at the base (ie dia issue) If cases were fired in another rifle with a larger dia chamber, you may not be able to resize them enough, period...
Finally, if you're not lubing the inside of the neck adequately, the expander ball may be pulling on the neck and shoulder excessively to distort the case at the neck/shoulder junction. This can cause case binding problems - ask me how I know!
If you want to entertain yourself before the weekend, paint a sized case with a sharpie, and try to chamber it. You'll find out where the interference is...



























